The invention is in the general field of fluorescent lamps, particularly aperture-type fluorescent reprographic lamps used in copying documents and having a reflective coating of titanium dioxide disposed between the inner bulb wall and a phosphor layer for reflecting light outwardly through the aperture in addition to the light being emitted through the aperture directly from the phosphor layer. In one type of such aperture lamp, the aperture is in the form on an elongated region along at least a portion of the bulb length and is free from both phosphor and reflecting material and in another type the aperture is free from reflecting material but is covered with the phosphor. Such lamps are described in U.S. Pat. No. 3,875,455 which further describes the various different materials that can be used for the light reflector coating and for the phosphor composition. In more recently issued U.S. Pat. No. 3,886,396 it is disclosed that the reflected coating may consist entirely of magnesium oxide (MgO) and that a protective post-coating of finely divided aluminum oxide (Al.sub.2 O.sub.3) particles deposited directly upon the phosphor layer improves lamp maintenance as well as reduces end discoloration during lamp operation.
Because of the decrease in light output which still occurs during lifetime of a reprographic lamp, there still remains a significant need for additional improvement. It would also be desirable to obtain improved lamp maintenance by simple modification of the reflector layer itself as distinct from any requirement for additional layers within the lamp envelope or accompanying modification of the phosphor layer from that presently used.